Microbial colonization of exposed tooth surfaces (enamel and cementum) in the oral cavity has been demonstrated to be associated with biofilm formation and subsequent periodontal disease or dental caries. Studies have demonstrated that tooth surfaces and the surfaces of certain dental biomaterials that have higher surface roughness values have increased microbial attachment and adhesion in comparison with similar substrates that have been polished or glazed. However, initial investigations into the reduction of surface roughness or incorporation of antibacterial monomers in polymer-based restorative biomaterials have had limited success in reducing biofilm formation. The overall goal of this project is to determine the utility of selected topographical and physical properties as predictors of in vitro biofilm formation by Streptococcus mutans and by Streptococcus gordonii. The specific aims of this investigation are: 1) to characterize selected topographical and physical properties of tooth and restorative biomaterial surfaces and to measure biofilm accumulations of S. mutans and S. gordonfi on those surfaces, and 2) to quantify the effect of laser, chemical and mechanical treatments of tooth and restorative biomaterial surfaces on selected topographical and physical properties and S. mutans and S. gordonfi biofilm accumulation. The studies comprising this project will utilize atomic force microscopy to obtain non-destructive 3-dimensional topographical and nanohardness characteristics of the surfaces tested. A contact angle goniometer will be used to measure the surface energy and wettability/hydrophobicity of the substrates, and a confocal laser scanning microscope will be used to quantify the biofilms formed in an in vitro batch culture apparatus. It is hypothesized that accurate characterization of the topography of natural and synthetic dental substrates will provide significant fundamental information on the role of those surfaces in biofilm development, particularly in the proximity of restorations. The knowledge gained from this project will also be useful in the modification of the topography of existing dental restorative materials and periodontal treatments, or in the formulation of guidelines for new restorative materials and treatments. In the long-term, this knowledge could help to reduce the incidence of disease connected with biofilm formation, thereby realizing substantial cost savings and improved oral care for dental patients.